I don't own your same model (currently a Palazzo 33.2) but will try to answer as best I can.
1. If it comes with 4 batteries like my 2018 Palazzo did, then they are likely already 6V GC, which is good as they can be drawn down 50% of their capacity ~600 times verses only ~20% if they are 12V
2. If solar ready, it either comes with just wiring and connection and possibly a GoPower PWM30 controller, which both are good for 400W total max and they will only charge the house/coach batteries and not the chassis/starting. I'm not sure why, but from what I've read on this site and personally experienced, the chassis batteries don't seem to get charged for anyone while on shore, genny, or solar and I ran a separate battery tender to my chassis batteries when "storing" but later moved the factory 100W solar to the Chassis batteries when I added a dedicated 680W system for my House batteries.
3. Yes, the inverter (assuming it equipped with one) works directly off the house batteries and only feeds a sub-panel which powers all 110 plugs, TV, residential fridge (if equipped with one, this will be your biggest draw when not on shore or genny) and microwave (some models/years are not wired to inverter) but not high draw devices like the AC or water heater.
And yes, 4 house batteries would be better!
4. Yes the house batteries will charge while driving once the chassis batteries reach full charge, through an Bi-directional switch or by the solar if you have it installed. You may run your genny while driving if you want to run your main AC on hot days and it will also charge the house batteries.
5. Assuming yours is like mine, I had a 2000W inverter which feeds a sub-panel and all of the 110 outlets, fridge & micro.
If you can get the VIN you could call Thor tech support and find out exactly what options your's comes with and how they wired it.
I hope all of this is helpful and applicable to your specific model.
2018 Palazzo 33.2